Your guitar is in standard tuning.
Place your fingers on the second frets of the bottom E string and the G string. Strum all six strings. You have a D6add9 chord.
The bottom four strings produce a D major chord. The open B string provides the sixth note in a D major chord, making it a D6 chord.
I wondered why it is not called a D6add2, because the open E string provides the second note in the major scale. But of course the ninth note is also the second note, just an octave higher.
The E in the D6add9 comes from the top E string. It is the highest pitched note in the chord, and presumably that is why it is called D6add9 rather than D6add2.
Am I right?